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posted by martyb on Sunday September 12, @04:41AM   Printer-friendly [Skip to comment(s)]
from the what's-in-your-closet? dept.

A Laser Fired Through a Keyhole Can Expose Everything Inside a Room:

Being able to see inside a closed room was a skill once reserved for super heroes. But researchers at the Stanford Computational Imaging Lab have expanded on a technique called non-line-of-sight imaging so that just a single point of laser light entering a room can be used to see what physical objects might be inside.

Non-line-of-sight (NLOS, for short) imaging is by no means a new idea. It’s a clever technique that’s been refined in research labs over the years to create cameras that can remarkably see around corners and generate images of objects that otherwise aren’t in the camera’s field of view, or are blocked by a series of obstacles. Previously, the technique has leveraged flat surfaces like floors or walls that are in the line of sight of both the camera and the obstructed object. A series of light pulses originating from the camera, usually from lasers, bounce off these surfaces and then bounce off the hidden object before eventually making their way back to the camera’s sensors. Algorithms then use the information about how long it took these reflections to return to generate an image of what the camera can’t see. The results aren’t high resolution, but they’re usually detailed enough to easily determine what the object in question is.

The first link in the story is to a 3m39s YouTube video demonstrating the process in operation.


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  • (Score: 5, Insightful) by Anonymous Coward on Sunday September 12, @06:58AM (6 children)

    by Anonymous Coward on Sunday September 12, @06:58AM (#1177183)

    Good luck finding an unobstructed keyhole in any door installed since about 1950.

    --
    Of course, it's much easier to open the door and look. Oh,... and, "Don't make me come in there!"

    • (Score: 2) by FatPhil on Sunday September 12, @09:44AM (5 children)

      "Keyhole" is a metaphor. Did you watch the video, they simply used a drilled hole in the experiments?
      --
      I know I'm God, because every time I pray to him, I find I'm talking to myself.
      • (Score: 2) by Rich on Sunday September 12, @02:08PM (4 children)

        by Rich (945) on Sunday September 12, @02:08PM (#1177222) Journal

        There's yet another "Keyhole". One that can see about everything. It just occured to me as I happened to see one fly by just yesterday. KH-11 Block 4 Unit 1 to be precise. And to get back on topic, I wouldn't be surprised, if later blocks would have some kind of indirect laser sensing to make the headline true. :)

        • (Score: 2) by EvilSS on Sunday September 12, @06:29PM (3 children)

          by EvilSS (1456) Subscriber Badge on Sunday September 12, @06:29PM (#1177264)
          Sure, but how does it drill the hole for the laser to enter a room from space?
          • (Score: 2) by Rich on Sunday September 12, @08:37PM (2 children)

            by Rich (945) on Sunday September 12, @08:37PM (#1177296) Journal

            They just crank the laser power up a tick?

            Jokes aside, they probably can use a cluster of satellites to illuminate stuff from different angles and do analysis on the reflections.

            • (Score: 1) by khallow on Monday September 13, @10:11PM (1 child)

              by khallow (3766) Subscriber Badge on Monday September 13, @10:11PM (#1177516) Journal
              Just keep in mind that when you illuminate something you tell the target that you're watching. Generally, that's not part of the plan.
              • (Score: 2) by Rich on Tuesday September 14, @11:35AM

                by Rich (945) on Tuesday September 14, @11:35AM (#1177659) Journal

                Or you want to create the impression that you are watching from afar to distract from the fact that you have a mole on the ground. These are three-letter-agencies, after all. :)

  • (Score: -1, Troll) by Anonymous Coward on Sunday September 12, @02:41PM

    by Anonymous Coward on Sunday September 12, @02:41PM (#1177228)

    Just put a Bible on top of your Quran and you'll stay off the watchlists.

  • (Score: 1, Informative) by Anonymous Coward on Sunday September 12, @05:06PM

    by Anonymous Coward on Sunday September 12, @05:06PM (#1177244)

    First a nit: they're not using "a single optical path," but many. As they pointed out, previous work used a static object and they rastered the wall to get many data points. Here they are essentially doing the same thing where instead of rastering the wall, they are keeping their laser point constant on the wall, but moving the object. Six of one, half a dozen of the other.

    The object in this case is keeping its relative pose constant as they move it. They've also had to use long exposures and retro-reflecting tape to get decent signal return. Again, this is interesting work and nothing to pooh-pooh, but nowhere near progressed as far as the gizmodo article would imply. This would be one of those "one step closer to" type of papers.

    If I had to bet, if you had N objects in the room all moving and not maintaining their poses as they move, that the problem becomes intractable very quickly if you want to "image" what's in the room. There will probably be some scenarios where the restricted conditions would apply and this might be useful, but don't hold your breath for the special ops drill a hole in the wall and take a picture type of product.

  • (Score: 0) by Anonymous Coward on Monday September 13, @03:02PM

    by Anonymous Coward on Monday September 13, @03:02PM (#1177432)

    My first thought is that this really is crazy. I remember movies and video games from decades ago where some super spy would do "something" to see inside a room or around a corner. It seems like that science fiction is now true.

    My next thought was "is this really that special?" I mean if you already have a hole, can't we already put in a pin-hole camera to actually see where everything is anyway? I guess it could be useful for seeing around corners during some kind of assault into a house?

    Regardless, this is really a very clever idea. (And, in thinking of the recent Ig-Nobels, first shocked me and then made me think.) I would be curious to hear what people think about how much of this is a curiosity and how much of this is a proverbial game-changer. (Currently speaking, of course. Future developments could always show new applications or improvements which are currently unimaginable.)

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